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    Subject[PATCH 4.14 08/52] udp: fix rx queue len reported by diag and proc interface
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Paolo Abeni <pabeni@redhat.com>

    [ Upstream commit 6c206b20092a3623184cff9470dba75d21507874 ]

    After commit 6b229cf77d68 ("udp: add batching to udp_rmem_release()")
    the sk_rmem_alloc field does not measure exactly anymore the
    receive queue length, because we batch the rmem release. The issue
    is really apparent only after commit 0d4a6608f68c ("udp: do rmem bulk
    free even if the rx sk queue is empty"): the user space can easily
    check for an empty socket with not-0 queue length reported by the 'ss'
    tool or the procfs interface.

    We need to use a custom UDP helper to report the correct queue length,
    taking into account the forward allocation deficit.

    Reported-by: trevor.francis@46labs.com
    Fixes: 6b229cf77d68 ("UDP: add batching to udp_rmem_release()")
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    include/net/transp_v6.h | 11 +++++++++--
    include/net/udp.h | 5 +++++
    net/ipv4/udp.c | 2 +-
    net/ipv4/udp_diag.c | 2 +-
    net/ipv6/datagram.c | 6 +++---
    net/ipv6/udp.c | 3 ++-
    6 files changed, 21 insertions(+), 8 deletions(-)

    --- a/include/net/transp_v6.h
    +++ b/include/net/transp_v6.h
    @@ -45,8 +45,15 @@ int ip6_datagram_send_ctl(struct net *ne
    struct flowi6 *fl6, struct ipcm6_cookie *ipc6,
    struct sockcm_cookie *sockc);

    -void ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
    - __u16 srcp, __u16 destp, int bucket);
    +void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
    + __u16 srcp, __u16 destp, int rqueue, int bucket);
    +static inline void
    +ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp, __u16 srcp,
    + __u16 destp, int bucket)
    +{
    + __ip6_dgram_sock_seq_show(seq, sp, srcp, destp, sk_rmem_alloc_get(sp),
    + bucket);
    +}

    #define LOOPBACK4_IPV6 cpu_to_be32(0x7f000006)

    --- a/include/net/udp.h
    +++ b/include/net/udp.h
    @@ -244,6 +244,11 @@ static inline __be16 udp_flow_src_port(s
    return htons((((u64) hash * (max - min)) >> 32) + min);
    }

    +static inline int udp_rqueue_get(struct sock *sk)
    +{
    + return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
    +}
    +
    /* net/ipv4/udp.c */
    void udp_destruct_sock(struct sock *sk);
    void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
    --- a/net/ipv4/udp.c
    +++ b/net/ipv4/udp.c
    @@ -2720,7 +2720,7 @@ static void udp4_format_sock(struct sock
    " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
    bucket, src, srcp, dest, destp, sp->sk_state,
    sk_wmem_alloc_get(sp),
    - sk_rmem_alloc_get(sp),
    + udp_rqueue_get(sp),
    0, 0L, 0,
    from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
    0, sock_i_ino(sp),
    --- a/net/ipv4/udp_diag.c
    +++ b/net/ipv4/udp_diag.c
    @@ -163,7 +163,7 @@ static int udp_diag_dump_one(struct sk_b
    static void udp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
    void *info)
    {
    - r->idiag_rqueue = sk_rmem_alloc_get(sk);
    + r->idiag_rqueue = udp_rqueue_get(sk);
    r->idiag_wqueue = sk_wmem_alloc_get(sk);
    }

    --- a/net/ipv6/datagram.c
    +++ b/net/ipv6/datagram.c
    @@ -1026,8 +1026,8 @@ exit_f:
    }
    EXPORT_SYMBOL_GPL(ip6_datagram_send_ctl);

    -void ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
    - __u16 srcp, __u16 destp, int bucket)
    +void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
    + __u16 srcp, __u16 destp, int rqueue, int bucket)
    {
    const struct in6_addr *dest, *src;

    @@ -1043,7 +1043,7 @@ void ip6_dgram_sock_seq_show(struct seq_
    dest->s6_addr32[2], dest->s6_addr32[3], destp,
    sp->sk_state,
    sk_wmem_alloc_get(sp),
    - sk_rmem_alloc_get(sp),
    + rqueue,
    0, 0L, 0,
    from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
    0,
    --- a/net/ipv6/udp.c
    +++ b/net/ipv6/udp.c
    @@ -1503,7 +1503,8 @@ int udp6_seq_show(struct seq_file *seq,
    struct inet_sock *inet = inet_sk(v);
    __u16 srcp = ntohs(inet->inet_sport);
    __u16 destp = ntohs(inet->inet_dport);
    - ip6_dgram_sock_seq_show(seq, v, srcp, destp, bucket);
    + __ip6_dgram_sock_seq_show(seq, v, srcp, destp,
    + udp_rqueue_get(v), bucket);
    }
    return 0;
    }

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